Resolve 502 Bad Gateway errors encountered by Nginx + PHP (FastCGI) _linux

I have to follow the following two steps to resolve, and finally in the 2nd step in the FastCGI timeout time increased to 300, the problem is resolved:
PS: More envy of the Thunder Web server, 16G memory.
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1, see the current number of PHP fastcgi process is sufficient:
Netstat-anpo | grep "php-cgi" | Wc-l
If the actual number of "fastcgi processes" is close to the preset "fastcgi process", then the "fastcgi process count" is not sufficient and needs to be increased.
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2, some of the PHP program execution time than the Nginx wait time, you can appropriately increase the nginx.conf configuration file fastcgi timeout time, such as:
......
http
{
......
Fastcgi_connect_timeout 300;
Fastcgi_send_timeout 300;
Fastcgi_read_timeout 300;
......
}
......